1. Field of the Invention
This disclosure relates to: a high-voltage power-supply apparatus for outputting a high output voltage by controlling a piezoelectric transducer; and an image formation apparatus of the electrophotographic type or the like that employs the high-voltage power-supply apparatus.
2. Description of Related art
A conventional high-voltage power-supply apparatus outputs a high voltage by controlling a piezoelectric transducer in accordance with an output signal from a voltage-controlled oscillator (VCO) as described in Patent Document 1 mentioned below. Here, the piezoelectric transducer is a device capable of generating a high voltage from an inputted low voltage using the resonance phenomenon of a piezoelectric vibrator. Furthermore, upon application of a heavy load such as a load short-circuit, the conventional high-voltage power-supply apparatus forcedly confines the control frequency to a predetermined range by reversing the controlled polarity of an output to the VCO according to an output signal from an error amplifier (see, for example, Patent Document 1: Japanese Patent Application Publication No. 11-252905).